Managing for wildlife:
To become a good wildlife manager you must learn the essentials about the animal
you plan to manage: where it lives, how it lives, and what it needs to survive, flourish
and reproduce.  Creating a good Tree Swallow nest box project requires learning
some basic Tree Swallow characteristics and habitat needs.  

What do Tree Swallows look like?
Tree Swallows, scientific name Tachycineta bicolor, are small songbirds.  Like all
swallows they are fast, agile fliers that catch insects in their mouths as they fly.  
Tree Swallows show the typical swallow body plan:
  • Slender, streamlined bodies with short necks.
  • Long, pointed wings.
  • Small bills (but mouths that open wide).
  • Very short legs with small feet.

Most adult male and female Tree Swallows can be told from other swallows by their:
  • Shiny, iridescent blue upper body and head.
  • Pure white throat and body underside.
  • However, females in the spring of their second calendar year of life (their first
    nesting season) show a mix of brown and greenish upper body feathers, like
    those of the second-year female in Euan Reid's photo below.

  • Juveniles, young Tree Swallows that have recently left their nests and have not
    begun molt, are sooty gray above and white underneath.  During this brief stage
    they show no blue or greenish feathers.  Photo below by John Gavin.

Where do Tree Swallows live?
  • Tree Swallows nest from subarctic northern Canada and Alaska south through
    much of the United States.  
  • The green areas of the map below show their main breeding range, but they
    nest locally farther south.  
  • Field guides, local bird clubs, or state conservation departments can tell you if
    Tree Swallows nest where you live.
  • Tree Swallows winter from Florida and the Gulf Coast south into Mexico, Central
    America, and the Caribbean (red areas of the map).
  • Very specific range and occurrence data for Tree Swallows and other birds can
    be found by exploring the eBird database.

What do Tree Swallows eat?
  • All swallows are aerial insectivores: highly-maneuverable, active-pursuit
    predators that feed mainly on insects they hunt, chase, catch and eat in flight,
    as the Tree Swallow in Robert Whitney's photo below is about to do.

  • Aquatic insects of the Order Diptera, the true flies, are the most common prey
    taken, but Ephemeroptera (mayflies), and Odonata (dragonflies) are also
    preferred prey.  A variety of terrstrial insects are also consumed.
  • However, unlike other swallows, Tree Swallows eat certain berries, especially
    those of bayberry and waxmyrtle.  These berries become very important
    sources of food in autumn and winter.
  • Because they are such skillful fliers Tree Swallows are able to drink and bathe
    on the wing, as the ones in Stephen Kolbe's photo below are doing.

What type of natural nesting habitat do Tree Swallow like?
  • Tree Swallows prefer to nest near or in wetlands, such as marshes, swamps,
    beaver ponds, and wet meadows.
  • These wetlands are usually rather open for easy flight and have lots of the flying
    insects Tree Swallows prefer to feed themselves and their young.
  • Perhaps most important, wetlands often have nest sites Tree Swallows need.

Where do Tree Swallows build their nests under natural conditions?
  • Tree Swallows are cavity-nesters.  They nest inside holes in trees.
  • However, Tree Swallows are unable to dig their own nest cavities.  Under natural
    conditions they must find an old woodpecker hole or a cavity in a dead tree if
    they are going to raise any young.  Photo below by Heather V. Hogg.

  • Perhaps because there is usually a shortage of natural nest sites, Tree
    Swallows quickly accept nest boxes, even ones far from water.  
  • And although they are not colonial like some other swallow species, pairs of
    Tree Swallows will nest as close as 100' from one another if there are suitable
    nest sites and a good food supply.  This lets us create Tree Swallow projects
    with multi-box grids.

  • Tree Swallows are short-lived and may only get one or two chances to breed.  
    This, plus the shortage of nest sites, leads some Tree Swallows, like the one in
    Cheryl Sutton's photo below, to try nesting in risky or inappropriate situations.

You are going to learn a tremendous number of other things about Tree Swallows, but
understanding these basics lets you take your next step: finding a good location for
your nest box project.

Click here for Next Step: Finding Good Sites for Tree Swallow
Nest Boxes.

Tree Swallow Characteristics and Nesting Requirements
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